Study Of NMR Well Logging Application --Evaluation Of Reservoir Porous Medium And Identification Of Oil-Water In XX Oil Field

On the basis of the NMR processing software HERS 1.4, response characteristics of different reservoir fluids in NMR well logging are concluded, along with comprehensive well logging data. The research is conducted in XX oil field where porosity and permeability are low, porous medium structure and geology distribution are complex, multiple oil qualities (natural gas, light oil, intermediate oil and heavy oil) exist, and oil-water distribution is complex. The application of this research is to generalize and differentiate different reservoir characteristics, with the help of the reserve qualitative analysis of water-oil-gas reservoir. In order to increase the accuracy of the computation of permeability and mobile fluid porosity, dynamic T2 cutoff is calculated in the process of calculating irreducible water saturation and permeability coefficients with NMR data. Porous medium structures, in terms of the development of reservoir micro pores and large pores, are obtained by studying pore diameter distribution curve with NMR data. Porous medium and non-oil reservoir are easily distinguished with this research.The response characteristics of oil viscosity and various fluids (water, light oil, intermediate oil, heavy oil and water flooded layers) on four different NMR well logging equipment; i.e., MRIL_C, MRIL_P, CMR and MREX, are studied through the interpretation of NMR data using software. The identification of light oil and water by use of difference spectrum, frequency spectrum, cutoff-morphological analysis, TDA-apparent T1 and T2, and DIFAN-intrinsic T2 is completed. The identification of heavy oil and water by use of cutoff-morphological analysis, spectral displacement geometric average comparison, and mobile porosity-resistivity analysis is completed. Pseudo capillary pressure curves are converted by use of T2 distribution for the study of porous medium structure and oil production prediction. Three approaches of reservoir porous structure evaluation; i.e.,2D equal area, T2 geometric average fitting, and tri-porosity analysis are further studied.The calculation of alkane saturation by use of the vertical and horizontal relaxation time of oil-water systems and the bi-TE well logging is concluded and improved on the basis of oil-water identification for XX oil field where different reservoir and fluids are present. Dynamic T2 cutoff approach is concluded from corresponding experimental data, along with various porous medium evaluation methods. Comparisons are made between NMR T2 distribution and core capillary pressure curves, and the similarity are concluded. T2 distribution is used to convert capillary distribution curves, and thus, reservoir capacity can be evaluated through the calculation of different parameters. Pore structure is then studied on the basis of the above procedures. Finally, a standard that is used to identify different reservoirs and oil-water layers is built, through the analysis of various field data in XX oil field.